The preparation of diazaspirodecan-2-ones, in particular, 8-[{1-(3,5-Bis-(trifluoromethyl)phenyl)-ethoxy}-methyl]-8-phenyl-1,7-diaza-spiro[4.5]decan-2-ones, for example, (5S,8S)-8-[{(1R)-1-(3,5-Bis-(trifluoromethyl)phenyl)-ethoxy}-methyl]-8-phenyl-1,7-diazaspiro[4.5]decan-2-one (the compound of Formula I) is disclosed in U.S. Pat. No. 7,049,320, issued May 23, 2006 (the '320 patent) which is incorporated herein by reference in its entirety.

The novel compounds disclosed in the '320 patent are classified as Tachykinin compounds, and are antagonists of neuropeptide neurokinin-1 receptors (referred to herein for convenience as “NK-1 receptor antagonists”).
The compounds described in the '320 patent are classified as tachykinin compounds, and are antagonists of neuropeptide neurokinin-1 receptors (herein, “NK-1” receptor antagonists). Other NK1 receptor antagonists and their synthesis have been described, for example, those described in Wu et al, Tetrahedron 56, 3043-3051 (2000); Rombouts at al, Tetrahedron Letters 42, 7397-7399 (2001); Rogiers at al, Tetrahedron 57, 8971-8981 (2001) and in each of the following publications: published international application no. WO05/100358; U.S. Pat. No. 5,760,018 (1998); U.S. Pat. No. 5,620,989 (1997), and international publication nos. WO 95/19344 (1995), WO 94/13639 (1994), and WO 94/10165 (1994), each of which are incorporated herein in their entirety by reference.
“NK-1” receptor antagonists have been shown to be useful therapeutic agents, for example, in the treatment of pain, inflammation, migraine, emesis (vomiting), and nociception. The novel NK-1 compounds disclosed in the above-mentioned '320 patent include the compound of Formula I, which is useful in the treatment of nausea and emesis associated with chemotherapy treatments (Chemotherapy-induced nausea and emesis, CINE). Emesis and nausea have been a problem in the provision of chemotherapy. Chemotherapeutic agents, for example, cisplatin carboplatin and temozolomide have been associated with both acute and delayed onset nausea and vomiting. It is known to administer chemotherapeutic agents with an anti-emetic, for example, as described in U.S. Pat. No. 5,939,098, which describes coadministration of temozolomide and with ondansetron, however such therapy is not effective in preventing delayed onset nausea and vomiting.
As reported in the '320 patent, the compound of Formula I was characterized by TLC and by GC/MS techniques. The procedures described in the '320 patent yielded the compound of Formula I in the form of an amorphous white foam. Repeated attempts to crystallize the free base have not provided a crystalline material.
In general, compounds which have been identified as having therapeutic activity must be provided in a highly pure form for pharmaceutical use. Moreover, it is desirable to provide compounds intended for pharmaceutical use in a form such that it is handled easily for incorporation into a medicament, and when incorporated into a medicament the compound possesses a sufficiently robust character that it is resistant to chemical degradation, and thereby imparts a long shelf life to the medicament.